Naturally-occurring threats
Naturally occurring biological threats will become more deadly and transmissible than we see now with COVID-19. Increasing air travel, mass market food production, climate changes, urbanization, and increasing human-wildlife interactions only add to the growing risk and frequency of natural infectious diseases.
Human-generated attacks and accidents
Some old and many modern breakthroughs in biotechnology allow countries and terrorist organizations to produce biological weapons. Accidental releases of pathogens are also increasingly likely today as nations build more high-containment laboratories and conduct more risky biomedical research.